瓦斯压力影响下煤岩力学性质与冲击能量指数演化规律及机制  

Mechanical properties and impact energy index of coal affected by gas pressure and evolutionary mechanism

作　　者：丁鑫[1] 肖晓春[1] 潘一山[1,2] DING Xin;XIAO Xiaochun;PAN Yishan(School of Mechanics and Engineering,Liaoning Technical University,Fuxin 123000,China;School of Environment,Liaoning University,Shenyang 110136,China)

机构地区：[1]辽宁工程技术大学力学与工程学院,辽宁阜新123000 [2]辽宁大学环境学院,辽宁沈阳110136

出　　处：《煤田地质与勘探》2022年第7期98-106,共9页Coal Geology & Exploration

基　　金：国家自然科学基金项目(51974186);辽宁省科技厅博士启动基金项目(2021-BS-271);辽宁工程技术大学创新团队项目(LNTU20TD-17)。

摘　　要：深部煤层冲击地压诱发瓦斯涌出、突出事故频繁发生,对井下安全生产带来了巨大威胁,厘清瓦斯对煤岩力学性质、冲击倾向性演化规律是建立有效防治手段的基础。运用物理试验方法,基于自主研发的可视化煤岩流−固耦合试验系统,研究瓦斯压力影响的煤岩吸附、力学性质及碎块分布规律,分析瓦斯影响的煤岩冲击能指数演化特征与机制。结果表明:具有强冲击倾向性煤岩的瓦斯等温吸附曲线符合Langmuir模型,随瓦斯压力升高,煤岩软化特性越发明显,弹性模量、软化模量均呈阶段性降低,瓦斯对二者在煤岩峰值前后具有不同的影响效果且存在临界压力,试样破坏形式呈“脆性张拉→剪切→张拉+塑性流动”过渡,冲击能指数与试样碎块尺度均呈先减小后增大的“V”形变化特征,破碎后具有更多盈余能;含瓦斯煤岩小尺度碎块是灾害发生的客观条件,瓦斯膨胀能为煤体动态失稳提供了额外的能量,增大了冲击地压发生过程的强动力性和破坏性,这种煤岩基质骨架与瓦斯运移的固−流耦合降低了冲击地压发生的临界指标且具有更高的致灾潜能。研究成果与启示为进一步判定深部高瓦斯煤层灾变倾向并建立行之有效的防治手段提供了试验基础和研究思路。The frequent occurrence of gas emission and outburst accidents caused by rock bursts in deep coal seams poses a great threat to safe underground production.Therefore,clarifying the evolution law of the mechanical properties and burst potential of gas on coal and rock is the basis for establishing effective prevention and control measures.Using the self-developed visual coal fluid-solid coupling test system,we carried out the physical experiment to study the gas adsorption,mechanical properties and fragment distribution of coal affected by gas pressure,and analyzed the evolution characteristics and mechanism of the bursting energy index.The results show that the gas isotherm adsorption curve of coal with strong burst potential conforms to the Langmuir model.With the increase of gas pressure,the softening characteristics become more obvious,the elastic modulus and the softening modulus decrease in stages,where the gas has different effects on them before and after the stress peak of coal and there is a critical pressure.The impact energy index and the fragment size of the samples show a“V”type change characteristic of first decreasing and then increasing.Their failure modes are“brittle tension→shear→tension+plastic flow”,and there is more surplus energy after fragmenta-tion.The small-scale fragments of gas-bearing coal are the objective condition for disaster occurrence.The gas expan-sion energy provides additional energy for the dynamic instability of coal mass,which increases the strong dynamic and destructive nature of the occurrence process of rock bursts,and the solid-fluid coupling of coal matrix framework and gas migration reduces the critical index and has a higher disaster-causing potential.The research results and enlighten-ment provide an experimental basis and ideas for accurately determining the catastrophic liability of deep coal seams with high gas pressure,and develope effective prevention and control methods.

关 键 词：煤岩力学性质 冲击能量指数 冲击地压 高瓦斯煤层 瓦斯吸附特征 分形维数 

分 类 号：TD315[矿业工程—矿井建设]